How do you know if a question is meaningful?

As a child I thought that the question "why is the sky blue?" was unanswerable. As it turns out, this question is commonly answered using refraction in the atmosphere etc. However, if you now ask, "why is the night sky black?", the best answer you will get is Olber's paradox - it's black because it's not light. Therefore it seems that the real question of why the night sky is black is not answerable.
So my question is, how do we know which questions can be answered and which are meaningless? It seems as though the question "why is the day sky blue" is answerable whereas "why is the night sky black" is unanswerable.

Yes I suppose this is a problem if I don't properly define the term "meaningful". I mean meaningful in a similar way to answerable. Does the question have an objective (as far as objective can be) answer.

Yes I suppose this is a problem if I don't properly define the term "meaningful". I mean meaningful in a similar way to answerable. Does the question have an objective (as far as objective can be) answer.

It sounds like you are asking how you can know if a question has a satisfying answer or not. "Why is the sky blue" and "why is the sky black at night" both have answers, it's just that for some reason one of the answers is satisfying to you and one is not . Talking about refraction still doesn't explain why blue is blue instead of some other color. You can always trace a question back to unanswerable levels. In science and philosophy we attempt to explain these questions on increasingly deeper levels, but there will always be a dead end where we just can't answer "why."

Whether or not a question has meaning in philosophy generally has to do with whether or not it makes sense to ask at all. It is meaningless to ask, for example, "is the number 3 happy or sad." Numbers don't have emotions - the question doesn't make sense.

Is there no general rule to see if a question might be meaningful? I think the logical positivists discussed this. The thing with the answers of refraction and Olber's paradox is they are really answering different questions. Perhaps neither actually answers "why is the sky blue/black", which has the answer "our brain perceives this wavelength/no light as blue/black".

Is there no general rule to see if a question might be meaningful? I think the logical positivists discussed this. The thing with the answers of refraction and Olber's paradox is they are really answering different questions. Perhaps neither actually answers "why is the sky blue/black", which has the answer "our brain perceives this wavelength/no light as blue/black".

We see colour by using the Cones in our eyes. The night sky appears black because there is not enough light coming into our eyes to register the colour. In reality though the sky during the night time is blue. Same as the day. Go out into a empty field far away from city lights and look up to the moon and the sky is definitely blue. Why does it look black? Well because of the lower intesity of moonlight vs. sunlight we are able to see into outerspace. Which is black for an answer on that go to NASAs website.

Moonlight is something like 10 million times less bright than sun light.
Do a google image search for nighttime pictures with a full moon. I assure you the ones that look like they were taken in the daytime were taken during the night.

This is not a meaningless question at all.

Meaningless questions in my opinion are ones that serve no purpose. As long as there is a purpose to the question then it is meaningful to someone... I.e. Someone said that 'How does the Number 3 feel.' was a meaningless question.
Sure it's a meaningless question to YOU because you say numbers have no feelings. What about other people who don't know if numbers have feelings? Imagine your child asked that and you said 'Don't ask meaningless questions' Does the kid leave the situation knowing that meaningless means numbers have no feelings? Or does he leave the situation thinking its meaningless because obviously numbers have feelings and the number 3 is always happy...

Is there no general rule to see if a question might be meaningful? I think the logical positivists discussed this. The thing with the answers of refraction and Olber's paradox is they are really answering different questions. Perhaps neither actually answers "why is the sky blue/black", which has the answer "our brain perceives this wavelength/no light as blue/black".

The positivists did discuss it. The positivist stance was that it is meaningless to ask questions like "what is real?" or "is murder bad?" because the answers cannot be tested scientifically. This is not a generally accepted view in current philosophy.

I would also disagree that referencing our brains provides a final and unquestionable answer. I can ask, "are my thoughts actually reducible to functions of my brain?" or "how do signals in my brain make me see this blue color?" There are also quantum physicists who would disagree with you on your assumption that wavelength is any more basic than color.

The general rule is that if a question is just nonsense, it's meaningless. Besides that, it's an open debate.

Meaningless questions in my opinion are ones that serve no purpose. As long as there is a purpose to the question then it is meaningful to someone... I.e. Someone said that 'How does the Number 3 feel.' was a meaningless question.
Sure it's a meaningless question to YOU because you say numbers have no feelings. What about other people who don't know if numbers have feelings? Imagine your child asked that and you said 'Don't ask meaningless questions' Does the kid leave the situation knowing that meaningless means numbers have no feelings? Or does he leave the situation thinking its meaningless because obviously numbers have feelings and the number 3 is always happy...

A general explanation of meaning in this context is that statements with truth values are meaningful. "The number three is happy" is neither true nor false; it is meaningless. Numbers, by their standard definition, can't be happy or unhappy. It is perfectly reasonable to wonder about and debate which statements have meaning.

Making fun of a child for asking if "3" is happy would be ridiculous. It would also be (logically) ridiculous to answer, "yes, 3 is happy today."

A general explanation of meaning in this context is that statements with truth values are meaningful. "The number three is happy" is neither true nor false; it is meaningless. It is perfectly reasonable to wonder about and debate which statements have meaning.

Numbers don't have feelings is truth (by definition of numbers); it is not meaningless.

Because something looks so simple and easy to answer to you does not imply it's a meaningless question (objectively). Although it sounds to me like you're trying to say truths are objective and everyone knows them a priori.

Again go ahead and tell a child that "the number three is happy" and see if he figures out if it is neither true or false.

If YOU asked 'How does number 3 feel' then yeah it's probably meaningless because you're asking it without a purpose.

The question "are my thoughts actually reducible to functions of my brain?" seems unanswereable to me. In fact I am convinced they are not, but I see no way to objectively show this to another person. If I see the question as meaningless and you see it as meaningful, is there no way to settle the matter?
To complicate things I could add a distinction between meaningless and unanswerable. We might assume that the question "does God exist?" has an answer but that we can never know. In this case it would be meaningful but unanswerable.

The question "are my thoughts actually reducible to functions of my brain?" seems unanswereable to me. In fact I am convinced they are not, but I see no way to objectively show this to another person. If I see the question as meaningless and you see it as meaningful, is there no way to settle the matter?
To complicate things I could add a distinction between meaningless and unanswerable. We might assume that the question "does God exist?" has an answer but that we can never know. In this case it would be meaningful but unanswerable.

You should go and read my post before you go around spreading misinformation about the sky being black at night any more. lol :)

Numbers don't have feelings is truth (by definition of numbers); it is not meaningless.

That's exactly what I said above. Not sure what your point is here. I also never claimed that truth can be known at all. A person can be happy. It is therefore meaningful to ask, "is Tom happy?" Number cannot be happy. It is therefore meaningless to ask, "is 3 happy?"

I also never claimed that it is simple to figure out which questions are meaningful and which are not.

We're talking about questions themselves. "Is Tom happy?" has one meaning and only one meaning, regardless of who asks it. Words have definitions and when you put words in sequence you get a statement with a single defined meaning.

Whether or not a person asks what they are trying to ask or knows how to accurately use language is irrelevant and does not change the meaning of the words they actually use.

That's exactly what I said above. Not sure what your point is here. I also never claimed that truth can be known at all. A person can be happy. It is therefore meaningful to ask, "is Tom happy?" Number cannot be happy. It is therefore meaningless to ask, "is 3 happy?"

I also never claimed that it is simple to figure out which questions are meaningful and which are not.

We're talking about questions themselves. "Is Tom happy?" has one meaning and only one meaning, regardless of who asks it. Words have definitions and when you put words in sequence you get a statement with a single defined meaning.

Whether or not a person asks what they are trying to ask or knows how to accurately use language is irrelevant and does not change the meaning of the words they actually use.

No... you said the number 3 is HAPPY is meaningless. I would answer numbers don't have feelings so therfore my answer is MEANINGFUL how can a question have a meaningful answer yet be meaningless?

EDIT: Noticed you editted your post like 3 times after I quoted it lol hmm.... I never implied making fun of a child. The fact of the matter is that they can ask that question and it is meaningful. You are just giving a blanket answer saying questions like those are meaningless. I disagree and think it has to do with the purpose and intent of the question to the individual asking it. A person knows if a question they asked is meaningless to a situation no one else can say whether or not it is meaningless though.

Eg. For me the question 'do meaningless questions exist?' is a meaningless question and I wouldn't ask it because I have no purpose/intent with your answer. This can of course change over time...

And just because a question has one meaning does not mean the answers are all the same. Eg. What colour the majority of this dress:

I agree that a child can ask a meaningless question and receive a meaningful response that helps enlighten them about their original question. I do not think that the utility of a question has anything to do with whether or not it is meaningful.

I think I am using the word "meaning" in a more axiomatic logical sense. I don't agree that truth is relative and one question can have more than one correct answer. Two people can give two different answers about what color the dress is, but at least one of them is wrong.

So... meaningless questions do exist, since you've just given an example of one? Oh wait, if meaningless questions exist then 'do meaningless questions exist?' itself is meaningful, and then then it's no longer a meaningless question...

I don't agree that truth is relative and one question can have more than one correct answer. Two people can give two different answers about what color the dress is, but at least one of them is wrong.

All Truth is relative in as much as it can only be derived through our own human experience(whatever its nature). This relative truth is descriptive of how we perceive things, not of how they fundamentally are or might be. If the universe is deterministic, our truth is relative to how we were pre-determined to react to its manifestation. Hence the Ultimate/Absolute Truth might be that a scientist from an advanced civilisation or some god or other unknown mechanism had laid out all of reality and its history for us.

All Truth is relative in as much as it can only be derived through our own human experience(whatever its nature). This relative truth is descriptive of how we perceive things, not of how they fundamentally are or might be. If the universe is deterministic our truth is relative to how we were pre-determined to react to its manifestation, and thus the Ultimate/Absolute Truth might be that a scientist from an advanced civilisation or some god or other mechanism had laid out all of reality and its history for us.

So... meaningless questions do exist, since you've just given an example of one? Oh wait, if meaningless questions exist then 'do meaningless questions exist?' itself is meaningful, and then then it's no longer a meaningless question...

My head hurts.

It's subjective to me. Selectively quoting and claiming I said something other than what I actually said will probably hurt your head. I said 'For me the question....'

What I've been saying in all my posts that you've probably missed is that meaning is a subjective term. So the reason I say it's a meaningless question is because I believe that meaning comes from the individual person. Which isn't directly the OPs question but I'm needing to argue out my point :) I still stand by what I said initially a meaningless question is one that has no purpose. Purpose is also subjective.

The colour of the dress is a good example. First you say that each word has a DEFINITIVE definition btu then you say people might give different answers? It's true that the dress is in fact only one colour but the subject perceptions each individual has will change. For instance Evo gave an answer I've never encountered with this type of question. She says chartreuse.

This answer is not wrong. Nor would be someone calling it 'highlighter yellow' or 'electric-lime' or just saying yellow or saying yellow-green. These are all good answers and all which I received in my philosophy class. Some people even went into neon colour descriptions. Thats how they PERSONALLY saw the colour. Of course we can go into the colour co-ordinates and determine its exact characteristics. I'm sure if we did this though you would find this dress is not chartreuse as Evo suggests although that's probably the closest resemblance of an answer I've gotten before.